Water towers are an engineering solution for increasing an area's water pressure. The basic principle is that water is pumped up into the water tower (essentially an elevated water tank) at night and then distributed to homes with an additional pressure boost from gravity. Large water towers are found in all sizes of large towns and small cities.
A Detailed Description
As stated before, water towers exist mainly to provide a pressure boost for municipal water systems. The force of gravity provides a boost of 0.43 PSI for each foot of height. A typical municipal water system runs at a pressure of 50 to 100 PSI (with 30 PSI as a bare minimum)1. A few quick calculations suggest that a water tower needs to be at least 116 to 232 feet above ground level to provide adequate pressure. In order to minimise the required height of the actual structure, water towers are often located near high points2.
All water towers work in basically the same manner and several standard designs exist. The tower can be a large tank on top of a pipeshaft with or without a supporting framework. Tall, narrow cylindrical standpipes are another design, or much larger, shorter cylinders3, too. Unelevated cylinder tanks are typically found on higher hills, using the landscape to provide gravitational force. Tanks are usually built of steel but can also be brick or concrete. Older water towers may even be constructed of iron or wood.
A water tower's tank is typically sized to hold a day's supply of water for that town. This allows for the water supply to an area to continue flowing with consistent pressure, even if the pumps fail temporarily. As a result, water towers can vary quite widely in volume. However, even smaller towns usually have a water tower with at least 100,000 gallons of water capacity.
Water towers also are necessary to handle the demands of peak usage on the system. A city's rate of water usage may vary significantly during a day. There are often surges in the mornings and evenings, contrasting with minimal usage at night. Without a water tower's reserves, a city would need a pumping station that works above the rate of peak consumption to handle demand. With a water tower in place, a city can instead use a much slower (and cheaper) pumping system. Peak demand is supplied directly from the water tower, and the pump refills the water tower at night.
Any style of tank can be enclosed in any variety of outer buildings, or the tank itself may be designed to look like something else. The Libby Foods plant in Rochester, Minnesota, features a water tower shaped like an ear of corn. Small towns can be dependent on one community water tower, larger towns and small cities may require two or three. Rural residents or farms that use well-water may need their own tower, as will larger businesses or production facilities that would put a strain on the local water supply. In big cities like New York it's necessary for some individual buildings to each have their own miniature water tower.
Historic Water Towers
Hoole Lane Locks water tower in Chester, England, was built in the 1320s. Still in use today, the tower belongs to the Chester Water Company. Two hundred miles southeast, 'Jumbo' is a triumphal arch water tower in one of Britain's oldest towns, Colchester, England. Built in 1882, the tower was taken out of service in 1987 and the structure has not found a new purpose yet.
The Weyburn Water Tower in Saskatchewan, Canada, was built in 1909 and removed from service in 1977. The exterior resembles a lighthouse and can be seen for miles by travellers approaching the town. The Weyburn Tower was designated as a Municipal Heritage Property in 1987.
The water tower at Randolph Air Force Base in Texas is housed in building 100, known as the 'Taj Mahal'. Built in the Spanish revival style, the two-storey building and tower were opened in 1931. The building also houses the headquarters for the base. The dome of the tower features a blue and gold mosaic tile roof, and the tank holds 500,000 gallons of water.
The Chicago Water Tower is one of the most famous in the United States. Completed in 1869, the tower survived the Great Chicago Fire of 1871, even though much of the surrounding area was destroyed. The tower is now obsolete but the pumping station is still in operation. The attraction is a stop on many guided tours of Chicago, Illinois.
The Lucerne Water Tower is Switzerland's most photographed landmark. Constructed around 1300, it was originally part of the city wall and has seen many uses over the centuries, including an archive and a prison.
The former Kotka water tower in Finland was built in 1914 atop the highest cliff in Kotkansaari. It served for a short while as a watchtower during the second World War. Used as a water tower until the 1960s, is now the Haukkavuori observation tower with a spectacular view and a cafe.
In Murtoa, Victoria, Australia, the water tower constructed in 1886 is no longer part of the water system. It now houses the historical society and local history museum.
Whimsical Water Towers
All across the United States it is common to see the 'tank on pipestem' variety of water tower in most communities. Without the fancy (or functional) outer structure to set them apart, some towers will be painted to look like other things, or feature designs that identify the community. Driving along America's highways you can see a number of apples, oranges, peaches and strawberries aloft, and the traditional smiley face is a popular facade. Some communities feature 'hot' and 'cold' towers, but in reality all the water is the same. No water towers are heated.
Stanton, Iowa, features a water tower in the shape of a floral coffee pot in honour of a local actress who was a coffee spokesperson in television commericals. When the tower was no longer viable, instead of tearing it down the town added a second tower - a matching floral coffee cup and saucer.
The World's Largest Catsup Bottle in Collinsville, Illinois, was the water tower for the old Brooks Tomato Products plant, which has since left town. Licking, Missouri boasts the World's Largest Baseball, the water tower for the Rawlings Sporting Goods factory, but the tower for the Five county Stadium in Zebulon, North Carolina, may be the second largest. Other 'World's Largest' claims include the pumpkin in Circleville, Ohio, and the watermelon in Luling, Texas4.
A bit further to the left of normal, the water tower in Metropolis, Illinois, sporting a likeness of Superman, is in danger of being torn down. The water tower in Cape Charles, Virginia, is designed to look just like the town's lighthouse. In Ogallala, Nebraska, passers-by can wave at the friendly aliens peeking out of the portholes of the town's UFO-themed water tower.